I think you might want to conduct your search the other way around and find a CRM solution that includes all of these. Help Desk is usually added on or integrated with larger CRM solutions. Soffront, Salesforce, and Microsoft Dynamics would probably all fit your needs.
QuickFMS provide Help Desk Software on cloud that delivers more than you need. You can take a demo of that and experience the features with less amount.
Explore more about QuickFMS's help desk software here:http://quickfms.com/helpdesk.php